1. Field of the Invention
The present invention relates generally to medical apparatus and methods for treatment. More particularly, the present invention relates to expandable prosthesis and methods for treating abdominal and other aneurysms.
Aneurysms are enlargements or “bulges” in blood vessels which are often prone to rupture and which therefore present a serious risk to the patient. Aneurysms may occur in any blood vessel but are of particular concern when they occur in the cerebral vasculature or the patient's aorta.
Of particular concern are aneurysms occurring in the aorta, particularly those referred to as aortic aneurysms. Aortic aneurysms are classified based on their location within the aorta as well as their shape and complexity. Abdominal aneurysms which are found below the renal arteries are referred to as infrarenal abdominal aortic aneurysms (AAAs). Suprarenal abdominal aortic aneurysms occur above the renal arteries, while thoracic aortic aneurysms (TAA's) occur in the ascending, transverse, or descending part of the upper aorta.
Infrarenal aneurysms are the most common, representing about seventy percent (70%) of all aortic aneurysms. Suprarenal aneurysms are less common, representing about 20% of the aortic aneurysms. Thoracic aortic aneurysms are the least common and often the most difficult to treat. Most or all present endovascular systems are also too large (above 12 F) for percutaneous introduction.
The most common form of aneurysm is “fusiform,” where the enlargement extends about the entire aortic circumference. Less commonly, the aneurysms may be characterized by a bulge on one side of the blood vessel attached at a narrow neck. Thoracic aortic aneurysms are often dissecting aneurysms caused by hemorrhagic separation in the aortic wall, usually within the medial layer. The most common treatment for each of these types and forms of aneurysm is open surgical repair. Open surgical repair is quite successful in patients who are otherwise reasonably healthy and free from significant co-morbidities. Such open surgical procedures are problematic, however, since access to the abdominal and thoracic aortas is difficult to obtain and because the aorta must be clamped off, placing significant strain on the patient's heart.
Over the past decade, endoluminal repair has been used to treat aortic aneurysms in about 50% of the patients, especially for those patients who cannot undergo open surgical procedures. In general, endoluminal repairs access the aneurysm “endoluminally” through either or both iliac arteries in the groin. The grafts, which are generally made using fabric or membrane tubes supported and attached by various stent structures, are then implanted, typically requiring several pieces or modules to be assembled in situ. Successful endoluminal procedures have a much shorter recovery period than open surgical procedures.
Present endoluminal aortic aneurysm repairs, however, suffer from a number of limitations. A significant number of patients after endoluminal repair experience leakage at the proximal juncture (attachment point closest to the heart) within two years of the initial procedure. While such leaks can often be fixed by secondary interventional procedures, the need to have such follow-up treatments significantly increases cost and is certainly undesirable for the patient. A less common but more serious problem has been graft migration. In instances where the graft migrates or slips from its intended position, open surgical repair is required or may require the use of another extender graft.
A particularly promising endoluminal graft is described in U.S. Publication No. 2006/0025853, which corresponds to related application U.S. application Ser. No. 11/187,471, the full disclosure of which has previously been incorporated herein by reference. That patent application describes the treatment of the aortic and other aneurysms with a double-walled filling structure which is filled with a hardenable material and cured in situ. The structure conforms to the shape of the aneurismal space and resists migration and endoleaks. The particular design described, however, may in some situations have certain drawbacks. For example, after initial treatment and depressurization of the aneurysm with a graft system, the thrombus often resolves over time resulting in changes to the size and shape of the aneurysm sac. This may lead to leakage and loss of graft apposition to the inside surface of the aneurysm, formation of hygroma in the space between the graft and the aneurysm surface, and enlargement of the aneurysm, all of which can eventually lead to graft migration and/or repressurization of the aneurysm sac. A rigid endoluminal graft may not accommodate these morphological changes in size and/or shape of the aneurysm after endoluminal graft repair over time.
For these reasons, it would desirable to provide improved methods, systems, and prosthesis for the endoluminal treatment of aortic aneurysms. Such improved methods, systems, and treatments should preferably provide implanted prosthesis which result in minimal or no endoleaks, resist migration, are relatively easy to deploy, have a low introduction profile (preferably below 12 F), and can treat most or all aneurismal configurations, including short-neck and no-neck aneurysms as well as those with highly irregular and asymmetric geometries. Further it would be desirable to provide fillable aneurismal grafts having the capability to adapt and accommodate changes in the size and/or shape of the aneurysm and maintain the position of the device and graft apposition and seal against the inside surface of the aneurysm. At least some of these objectives will be met by the embodiments described hereinafter.
2. Description of the Background Art
Grafts and endografts having fillable components are described in U.S. Pat. Nos. 4,641,653; 5,530,528; 5,665,117; and 5,769,882; U.S. Patent Publications 2004/0016997; and PCT Publications WO 00/51522 and WO 01/66038. The following patents and published applications describe endoframes and grafts having cuffs, extenders, liners, and related structures: U.S. Pat. Nos. 6,918,926; 6,843,803; 6,663,667; 6,656,214; 6,592,614; 6,409,757; 6,334,869; 6,283,991; 6,193,745; 6,110,198; 5,994,750; 5,876,448; 5,824,037; 5,769,882; 5,693,088; and 4,728,328; and U.S. Published Application Nos. 2005/0028484; 2005/0065592; 2004/0082989; 2004/0044358; 2003/0216802; 2003/0204249; 2003/0204242; 2003/0135269; 2003/0130725; and 2002/0052643.